A personal colorimetric dosimeter for nitrogen dioxide was developed. Tests were performed to determine the response of these strips to various concentrations of NO2. The dosimeter strips were satisfactory for approximate determinations of total exposure (concentration + time) of nitrogen dioxide. The total exposure was calculated in terms of time in minutes and ppm of nitrogen dioxide in the test gas. Tests were performed at 50, 100, and 300 ppm-minutes. The 300 ppm-minute test was performed at 300 ppm and 20 ppm concentrations. The low concentration (20 ppm) long time test gave a higher exposure indication than the high concentration (300 ppm) low time interval test. (Author/SH)